With youngster, scavenging in the chalk reef or training maybe.
No interactions present.
The dark backed bird is a GBB but the other one, in image two, is an immature Herring Gull. it is much smaller, with a silver-grey mantle and is generally much less robust.
.. perhaps an adoptee as they went everywhere together and the GBB was extremely tolerant?
Lat/Lng: 51.3879, 1.3553
OS grid ref: TR335707